1. Field of the Invention
The present invention relates to an electronic pickup camera capable of wireless transmission of picked-up image data to an external storage device, and to a control method thereof.
2. Description of the Related Art
A conventional electronic pickup camera converts an image signal, picked up by an electronic pickup element, into compressed data and stores the compressed data in a semiconductor storage medium provided in the camera. A semiconductor storage element is a popular storage medium for such an electronic pickup camera. In some cases, the semiconductor storage element is fixedly mounted in the camera, and in other cases it is detachably mounted in the camera. The capacity of the semiconductor storage element to store image data is generally limited, thus the element cannot store a large quantity of image data.
Since Semiconductor storage elements are expensive, it is popular practice to transmit image data temporarily stored in a semiconductor storage element to an external storage device and store the image data therein, instead of preparing a plurality of semiconductor storage elements to store a large amount of the picked-up image data in these semiconductor storage elements. Examples of the external storage device include personal computers (hereinafter referred to as PC(s)) and PDAs (personal digital assistants). The term “external storage device” used herein indicates an external device capable of storing transmitted image data.
When image data stored in a semiconductor storage element of an electronic pickup camera is ready to be transmitted to an external storage device, the electronic pickup camera and the external storage device are usually connected with a connecting cable for data transmission. Then, the electronic pickup camera is driven and controlled from the external storage device, and the image data stored in the semiconductor storage element is read out, transmitted and stored in a storage medium in the external storage device.
During the transmission of the image data, the electronic pickup camera and the external storage device need to be located within a length of the connecting cable for data transmission. Therefore, when the electronic pickup camera is used at a location remote from the external storage device, the electronic pickup camera needs to be brought into the range where it can be connected to the external storage device with the connecting cable for data transmission. Consequently, a method for transmitting image data picked up by an electronic pickup camera to an external storage device by using a telephone line (including a cellular telephone line) has been thought out.
In this manner, image data picked up by an electronic pickup camera has typically been transmitted to an external storage device via a telephone line (including a cellular telephone line) and stored in the external storage device.
When an operator of the electronic pickup camera determines that the image data transmitted to the external storage device no longer needs to be stored in the storage medium within the electronic pickup camera, the operator manually deletes the transmitted image data from the storage medium of the electronic pickup camera.
On the other hand, the image data picked up by the electronic pickup camera may be transmitted to an external device which does not have an image data recording capability (or which only has a storage capability insufficient to record image data stored in the semiconductor storage element in the camera). A cellular telephone and a printer are examples of external devices having no or little capacity to store image data.